A method of applying heat or cold to human or animal parts and a reusable compress utilized therein. The method involves saturating crystals of a water soluble acrylic polymer and a thickening agent through the porous fabric of a compress bag containing the acrylic polymer and the thickener. The compress is heated in a warm water or a microwave oven or cooled in a cool environment. The compress is applied to a human or animal part to warm or cool the body part. When the compress is no longer needed the gel is de-hydrated and the compress is easily stored for safe reuse.
